Minimalist Clock Tells Time with LEDs

Jeremy is an engineer with 10 years experience at his full-time profession, and has a BSME from Clemson University. Outside of work he’s an avid maker and experimenter, building anything that comes into his mind!

Jeremy is an engineer with 10 years experience at his full-time profession, and has a BSME from Clemson University. Outside of work he’s an avid maker and experimenter, building anything that comes into his mind!

No matter how many maker clock designs I see here, it always seems that someone comes up with a new interesting take on this centuries-old device. This latest clock comes to us from Peter Traunmüller, an electrical engineering student (who also works part-time in an electronics engineering role) out of Vienna, Austria. His clock uses a 60-bulb ring of programmable SK6812 RGB LEDs under frosted acrylic glass to display the time in style.

You can see details of his build via this imgur set, an abbreviated version of which is seen below. Perhaps you’ll be inspired to build your own similar model, but if not, he also has them available on Etsy if you’d rather go that route.

The clock, which was originally made as a Christmas present for his parents, started out with him modelling the drawing in Solid Edge. The model included the PCB and LED ring he’d be using, and he claims that “This helped immensely as some mechanical mistakes were avoided in the first version.”

The clock features a 3D-printed crossing pattern that supports the LEDs, with a triangular section in the top to house the electronics. Inside of this “X” frame snaps a round ring which is also 3D-printed. It’s glued to the front acrylic face with SMX hybrid polymer glue—similar to silicone—in order to hold everything together.

It’s a great looking build, and as you might suspect, Traunmüller’s background, as well as his personal stash of electronics helped quite a bit:

I’ve played around with these things for quite a while now and due to my
work and study environment are constantly surrounded by electronics
projects. I especially liked the idea of the really small 8pin microcontroller capable of doing all the clockwork. The first prototype
was done within a day with parts I had at home.

Electronics-wise, Traunmüller also went through several revisions, starting off with two perfboard versions, then eventually moving on to an etched PCB. This board features an ATtiny85 chip for control, as well as a DS3231 real-time clock (RTC) unit in order to keep everything synced up.

Time setting is accomplished with two buttons, and the default brightness can be set via a screwdriver on the bottom of the clock. A photoresistor (or light-dependent resistor, LDR) allows the LED brightness to adjust automatically for ambient lighting. This light sensor was mounted on the bottom of the clock in order to minimize interference from the LEDs themselves while measuring the light, along with the micro USB connector used to power the unit.

In his workds:

The first two versions of the board were soldered manually on perfboard to get a feeling for the functions needed for the clock to work. The light sensor was only added later on, after having to unplug the clock over night because of it’s really intense LEDs. Also the DS3231 real time clock was not that easy to get into, mainly because I initially thought that the internal oscillator would be precise enough.

I digitized the final schematics with Eagle and the board layout was done so that all components would then fit snugly into the printed case.

Looking back on this design, Traunmüller he notes that he could have used a small GPS module instead of the buttons and RTC. With any project like this, it seems like there is always one more thing that could have been done differently, at least in the creator’s mind!

That aside, he’s very happy with this build. He notes that:

It was a lot of work, but in the end the build stands for itself and I’ve gotten a couple of requests for building more clocks.

He also notes that his CAD model was helped along immensely by his friend and colleague Stephan and “his insane CAD skills.” It seems that since many projects require both electronic and mechanical skills, it’s always nice to have someone to lean on in the areas where you’re not quite as strong!

Jeremy is an engineer with 10 years experience at his full-time profession, and has a BSME from Clemson University. Outside of work he’s an avid maker and experimenter, building anything that comes into his mind!

Jeremy is an engineer with 10 years experience at his full-time profession, and has a BSME from Clemson University. Outside of work he’s an avid maker and experimenter, building anything that comes into his mind!